It is known from the specification of French published patent application FR2560368A to provide a heat exchanger of the above type in which the end portions of the tubes are sealingly mounted in holes formed in the header plate, on which the header casing is secured, and in which immobilising or locating means are provided for the purpose of opposing any relative displacement, in particular by pivoting or torsion, of the tube bundle with respect to the header plate. In heat exchangers of this known type, sealing between the end portions of the tubes and the edges of the holes formed through the header plate is generally obtained by means of an elastomeric or similar gasket, which overlies one face of the header plate and which is formed with collar portions engaged in the holes in the header plate, between the end portions of the tubes and the edges of these holes.
In the particular type of heat exchanger disclosed in the above mentioned French patent specification, the said immobilising means provide a rigid coupling between the bundle of tubes and the header itself. This coupling thus resists any relative movements of the bundle of tubes with respect to the header plate, which may be liable to occur when the heat exchanger is handled either before or during its fitting on a vehicle, or even after it is installed in the vehicle. Such relative movements, which are detrimental to sealing between the ends of the tubes and the edges of the holes through the header plate, tend to occur most often in the case where the tube bundle consists of a single row of aligned tubes.
Again in the heat exchanger described in the above mentioned French patent specification, the immobilising means include lugs which are engaged in slots formed in the edges of the fins of the tube bundle, or alternatively fingers which are engaged in aligned openings formed in the fins. This arrangement therefore has the disadvantage that it is necessary to provide fins of a particular or special form, so that standard fins cannot be used.